1. Field of the Invention
The present invention relates to agents for controlling plant growth and methods for their use and preparation. The invention particularly relates to a combination of an abscission agent and an amide-sulfuric acid adduct, which combination is characterized by synergistic defoliation activity.
2. Description of the Art
Special tissue regions at the base of a leaf, flower or fruit stalk, are responsible for the separation of plant organs such as leaves, flowers and fruit from the plant body. When the separation process begins, the cell walls in the separation zone become soft so that the separation of the organ (abscission) becomes possible through mechanical forces, for example, by wind, or by weight of the organ itself. This, however, often does not take place at the desired time or to a desired extent. Frequently, it is advantageous to achieve this process in a controlled manner at a certain time or stage in the development of a plant.
Controlled defoliation is of special economic importance because of the easier harvesting and accelerated ripening obtainable thereby in agricultural and horticultural crops. Abscission agents for inducing such defoliation, via hormonal regulation, are known. For example, thidiazuron, the common name for n-phenyl-n'-1,2,3-thiadiazol-5-yl urea, is a known cotton defoliant and has been registered for such purpose with the Environmental Protection Agency.
Defoliation also may be accomplished by leaf injury with certain herbicides. The herbicide may be of either the contact or systemic variety. A contact herbicide requires that a substantial portion of the plant be contacted with the active ingredient of the herbicide being applied. A systemic herbicide translocates through the plant and substantial surface contact is not required.
Many chemical agents have been found which are useful for the defoliation of plants, either through hormonal regulation or herbicidal injury, and have been registered with the Environmental Protection Agency for certain selected uses. Their effectiveness frequently varies greatly depending upon the climatic conditions, application rates, and the plant to which they are being applied. Thus, there still is need for an improved agent for effectively defoliating plants to facilitate harvest, for the destruction of plants for weed control, and the like.